Thin flexible film composition



Patented Feb. 9, 1937 UNITED STATES THIN FLEXIBLE FILM COMPOSITION PeterA. van der Meulen, New Brunswick, N. .L, assignor to John R. Ditmars,New Brunswick,

No Drawing.

Application July 18, 1938,

Serial No. 680,975

16 Claims.

This invention relates to a transparent sheet material and comprehends asubstantially moisture-impervious material.

In the copending application of Charles M.

Boyce, Serial No. 545,833, filed June 20, 1931, Patent 1,978,406 fortreating surfaces of fibrous materials, there is disclosed a filmforming composition which is capable of being formed into a transparentsheet and which is also suitable for a film coating for coating thesurface of materials. In one form the composition contains gelatin and aglycerinc phthalate ester. This composition, when drawn out into a filmto form a sheet or a coating for a sheet base, is transparent. Thesurface of the dried coating or film may be polished to a high gloss andit is extremely flexible. Under ordinary conditions the surface of thefilm is very smooth and non-tacky but under certain atmosphericconditions, that is, a high humidity and high temperature, thecomposition takes up moisture and becomes sticky and under extremeconditions it may become soggy.

By this invention a sheet of this nature may be produced which has allof the desirable physical properties of the sheet disclosed in theaforementioned Boyce application, that is, it is transparent; it may bepolished to a high gloss; and it is extremely flexible, and in additiona sheet made in accordance with this invention is substantiallyimpervious to moisture and oil. In accordance with the invention, thereis added to a film forming composition a practically insoluble compound.The compound is added to the film forming composition undercircumstances to produce a sus 35 pension therein in a fine state ofdispersion throughout the composition. In a gelatin film formingcomposition such as that described in the aforementioned Boyceapplication, the insoluble compound used for the purpose of making 40the composition impervious to moisture is a compound resulting from thereaction between a sulphonated oil such as sulphonated castor oil, oliveoil, etc., and a water-soluble salt of a metal belonging to any of thegroups of the periodic sysphonated oil which is virtually insoluble andto release the free oil in the sulphonated oil mass in tern exceptgroup 1. In making the gelatin com-.

an extremely fine state of dispersion throughout the gelatin mixture. Inthe presence of the gelatin the insoluble compound is also produced inan exceedingly fine state of dispersion and does not come out as acoalescing precipitateas in the 5 case where the gelatin is absent. Itis believed that the gelatin, in the finished form, forms a sponge-likestructure. The insoluble sulphonated oil compound fills the intersticesof this sponge-like structure and the free oil released by 10 virtue ofthe reaction between the sulphonated oil and the metal salt coats thegelatin structure. The oil protects the structure of the gelatin frommoisture and the insoluble compound in the interstices of thesponge-like structure prevents the 15 moisture from penetrating into orthrough the composition. Y

A film forming composition embodying this invention can be made up inaccordance with the following example which will serve to illustrate gthe proportions of the various ingredients and the procedure followed.For a small quantity of the film forming composition, 32 gms. of gelatinis swelled by letting the gelatin soak in 180 cc. of water for a periodof twelve hours. The swelled g5 gelatin is heated in a water bath to 120F. and while in a liquid state, 1 cc. of 50% acetic acid is added. Atthis time, a solution of calcium nitrate is added. The solution ofcalcium nitrate is made up by dissolving crystallized calcium nitrate in30 water. The quantities of water and nitrate used are adapted toproduce a solution of 1 gram mole per liter. Other suitable salts of thealkaline earths, such as calcium chloride, calcium acetate, and similarbarium salts, may be used.

As heretofore stated, these soluble salts of the alkaline earths areused for reacting with a sulphonated oil which is added to the mixtureafter the addition of the solution of calcium nitrate. In the case beingdescribed, 14 cc. of 40 molar calcium nitrate solution would be added tothe gelatin-acetic acid mixture. In any solution, the proper amount ofthe calcium nitrate solution to be added can be determined in thefollowing manner: 22 gms. of the sulphonated and neutralized castor oil,hereinafter more particularly described, is diluted with about cc. ofwater in a small Erlenmeyer flask, provided with a cork. The calciumnitrate solution is placed in a burette and added to the solution of thesulphonated oil, one-half cc. at a time. The flask is shaken vigorouslyafter each addition of calcium salt solution, to cause foaming. It willbe found that the addition of approximately 15 cc. of the calcium saltsolution will 5 nated oil. The substance here designated as sulphonatedoil is a sodium neutralized sulpho nated oil; for the purpose of thecomposition being described it is the sodium-neutralized product of thereaction of by weight of con-- centrated sulphuric acid (0. V.) and 70%by weight ofcastor oil. The reaction is carried,

out at a temperature below C., and requires approximately five hours.Such a sulphonated mass contains about 8.5% combined sulphurtrioxide80:. This product is treated with an equal'quantity of water, thoroughlystirred, and allowed to settle. The water is then drawn oil. The oil isthen neutralized with the proper quantity of caustic soda, 32 36. Anyother sulphonated oil such as olive oil is suitable for the purpose, buta sulphonated castor oil is preferred.

In the example being given, 22, gms. of the sulphonated mass is added to20 cc. of water and the mixture is added to the gelatin mixture. Theresult of the addition of the sulphonated mass is the production in themixture of the insoluble calcium salts and also of the separation of thefree castor oil in the sulphonated ofl, in an extremely fine state ofdispersion throughout the gelatin. The gelatin, and a small quantity ofthe remaining sodium salt of sulphonated oil act as protective colloidsto maintain the fine state of division of the oil and calcium salts.

' The same result can be obtained from the reaction of the sodiumneutralized sulphonated oil with' a soluble salt of any of thefollowingmetals: strontium, barium, zinc, cadmium, mercury, lead, aluminum,glucinum, tin, bismuth, etc.

After the sulphonated mass has been added, the following are addedsuccessively: a mixture of 150 cc. of water and 7 cc. of butyl alcohol,a mixture of 1.25 cc. of ammonia, 4.25 cc. of a 5% solution of phenol inwater, and 20 cc. of water, a mixture of 2.5 cc. of a 40% solution offormaldehyde and 45 cc. of water, and 100 cc. of water. The butylalcohol apparently serves two functions. During the coating process, itlowers the surface tension of the water and thus promotes a spreading ofthe composition; it also aids in tying the film to a paper when used asa coating, acting as an additional bonding link between the paper andthe coated film. Any one of the three isomers of butyl alcohol, primary,secondary or tertiary or mixture of these, may be used. I

r The formaldehyde serves to harden the gelatin; it is not an essentialingredient and can be dispensed with. However, the small quantity offormaldehyde mentioned seems to produce a firmer film which has lesstendency to squeeze in the process of smoothing the surface of the filmThe phenol (carbolic acid, U. S. P.) is simply a preservative. goodpreservative, which will prevent bacterial growth, may be substitutedfor the phenol.

Any other suitable soluble organic acid can be substituted for theacetic acid. The acetic acid is merely used to assist in the action ofthe water on the gelatin.

Beta naphthol or any other Ithasbeenfoundthattheclearne-and-resistancetopenctrationbymoistureareappreciably increased by using asulphonated caster oil'whichhasbeenfreedasnearlyaspo-i from inorganicsalts (especially sodium sulthey are present in the film forming coatingcomposition. The production of these soluble salts may, however, bereduced to' a minimum in the preparation of the film forming compositionby following the method described below. This latter .method is alsoless elpe'nsive than the former and it involves materials which are lesscostly, and saves the worh'of certain intermediate steps. As before, 38gms. of gelatin are soaked in 180 gms. of water for'a period of twelvehours. The gelatin is then heated in a water bath to 120' I". and 1 cc.of a 50% acetic acid is added. Thereafter a quantity of calcium oxide,previously slaked in water, not'quite sumcient to neutralize thesulphonated mass to be later added. is then added to the mixture.

The amount of calcium oxide to be added may be determined in thefollowing manner: A por- 7 tion of the sulphonated mass, hereafterdescribed, is weighed and diluted in cold water.

The mass is then titrated at once with'standsrd sodium hydroxidesolution. From the results of this titration the quantityof calciumoxide necessary for complete neutralization is readily calculated.Between and of the calculated quantity of calcium oxide is weighed out,ground in a mortar, slaked with water and then added to the gelatinwhich has been warmed to F. In addition, 1 cc. of concentrated ammoniumhydroxide is added at this time. To the quantity of water-soaked gelatindescribed above, the following is added: 1 gram of calcium oxide isadded together with 50 cc. of water and 1 cc. of ammonia.

The sulphonated mass referred to immediately above and which is nextadded to the mixture is the unneutralized product of the reaction of 30%by weight of concentrated sulphuric acid (0. V.)

and 70% by weight of castor oil. The reaction is carried out at atemperature below 35 C. and requires approximately five hours. In thismethod, as in the one previously described, any other sulphonated oilmay be used'but sulphonated castor oil is preferred.

During the addition of the sulphonated mass, the gelatin solution isstirred vigorously. In the illustrative case, a mixture of 22 gms. ofthe sulphonated mass and 50 cc. of water are added to the gelatinsolution. When the .addition of of ammonia, 10 cc. of water; and 45 cc.of water, 2.5 cc. of formaldehyde. Finally, there is added 100 cc. ofwater. The composition so formed is ready to be applied to the paper andshould be applied at once.

Strontium hydroxide or barium hydroxide and the like may be substitutedfor the calcium oxide used in this formula.

The emulsion so formed is readily drawn out into a film by any of thewell known methods for forming films and it can be formed into a film onany of the well known machines for forming cellulose films. After thecomposition is drawn into a film and thoroughly dried it may be polishedas by calendering or by pressure contact with a highly polished surface.The film so formed has many uses. Films of this kind having variouscolor eflects can readily be made by adding dyes and metallic powderssuch as the aluminum and bronze powders to the film forming emulsion.

It will be obvious that various changes may be made by those skilled inthe art in the details of the procedure in making, and the ingredientsof, the embodiment of the invention described above within the scope andprinciple of the invention as expressed in the appended claims.

I claim:

1. A composition for forming a continuous film comprising a mixturecontaining a film forming emulsion and a water-insoluble salt of asulphonated vegetable oil in a fine state of dispersion throughout theemulsion.

2. A composition for forming a continuous film comprising a mixturecontaining a film ,forming emulsion and the reaction products of awater.- soluble compound of a metal taken from the group consisting ofthe metals of the second to eighth groups inclusive of the periodicsystem and a sulphonated vegetable oil in a fine state of dispersionthroughout the emulsion.

3. A composition for forming a continuous film comprising a mixturecontaining a film forming emulsion and the reaction products of asubstance taken from the group consisting of strontium hydroxide, bariumhydroxide and calcium hydroxide and a sulphonated vegetable oil in afine state of dispersion throughout the emulsion.

4. A composition for forming a continuous film comprising a mixturecontaining a film forming emulsion and the products of the reactionbetween calcium hydroxide and a sulphonated vegetable oil ina fine stateof dispersion throughout the emulsion.

' composition for forming a continuous film comprising a mixturecontaining a film forming emulsion and the products of the reactionbetween calcium hydroxide and sulphonated castor oil in a fine state ofdispersion throughout the emulsion.

6. A composition for forming a continuous film comprising a mixturecontaining a film forming emulsion and the reaction products of awatersoluble salt of a metal taken from the group consisting of themetalsoi the second to eighth groups inclusive oi the periodic systemand a sulphonated vegetable oil in a fine state of dispersion throughoutthe emulsion.

'7. A composition for forming a continuous film comprising a mixturecontaining a film forming emulsion and the reaction products of awatersoluble salt of a metal taken from the group consisting of themetals of the second to eighth groups inclusive of the periodic systemand a sodium neutralized sulphonated vegetable oil in a fine state ofdispersion throughout the emulsion.

8. A composition for forming a continuous film comprising a mixturecontaining a film forming emulsion and the reaction products of awatersoluble calcium salt and a sodium neutralized sulphonated castoroil in a fine state of dispersion throughout the emulsion.

9. A thin continuous flexible film comprising a dry moisture-resistantcomposition including a film forming compositionv and a water-insolublesalt of a sulphonated vegetable oil in a fine state of dispersionthroughout the composition.

10. A thin continuous flexible film comprising a dry moisture-resistantcomposition including a film forming composition and the reactionproducts of a water-soluble compound of a metal taken from the groupconsisting of the metals of the second to eighth groups inclusive of theperiodic system and a sulphonated vegetable oil in a fine state ofdispersion throughout the composition.

11. A thin continuous fiexible film comprising a dry moisture-resistantcomposition including a film forming composition and the reactionproducts of a substance taken from the group consisting of strontiumhydroxide, barium hydroxide and calcium hydroxide and a sulphonatedvegetable oil in a fine state of dispersion throughout the composition.

12. A thin continuous flexible film comprising a dry moisture-resistantcomposition including a film forming composition and the products of thereaction between calcium hydroxide and sulphonatedvegetable oil in afine state of dispersion throughout the composition.

13. A thin continuous flexible film comprising a dry moisture-resistantcomposition including a film forming composition and the products of thereaction between calcium hydroxide and a sulphonated castor oil in afine state of dispersion throughout the composition.

.14. A thin continuous flexible film comprising a dry moisture-resistantcomposition including a film forming composition and the reaction prod-.ucts of a water-soluble salt of a metal taken from 15. A thincontinuous flexible film comprisinga dry moisture-resistant compositionincluding a film forming composition and the reaction products of awater-soluble salt of a metal taken from the group consisting oithemetals of the second to eighth groups inclusive of the periodic systemand a sodium neutralized sulphonated vegetable oil in a fine state ofdispersion throughout the composition.

16. A thin continuous flexible film comprising a dry moisture-resistant.composition including a film forming composition and the reactionproducts of a water-soluble calcium salt and a sodium neutralizedsulphonated castor oil in a fine state of dispersion throughout thecomposition.

PETER A. VAN DER MEULEN.

